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[POWERPC] Avoid unpaired stwcx. on some processors 

The context switch code in the kernel issues a dummy stwcx. to clear the
reservation, as recommended by the architecture.  However, some processors
can have issues if this stwcx to address A occurs while the reservation
is already held to a different address B.  To avoid this problem, the dummy
stwcx. needs to be paired with a dummy lwarx to the same address.

This adds the dummy lwarx, and creates a cpu feature bit to indicate
which cpus are affected.  Tested on mpc8641_hpcn_defconfig in
arch/powerpc; build tested in arch/ppc.

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Becky Bruce 2007-11-10 09:17:49 +11:00 committed by Paul Mackerras
parent 64c911a3f7
commit b64f87c16f
3 changed files with 24 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/powerpc/kernel/entry_32.S
View File

@ -251,6 +251,9 @@ syscall_exit_cont:
bne- 2f
1:
#endif /* CONFIG_44x */
BEGIN_FTR_SECTION
lwarx r7,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@ -717,6 +720,9 @@ restore:
mtctr r11
PPC405_ERR77(0,r1)
BEGIN_FTR_SECTION
lwarx r11,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))

6
arch/ppc/kernel/entry.S
View File

@ -251,6 +251,9 @@ syscall_exit_cont:
bne- 2f
1:
#endif /* CONFIG_44x */
BEGIN_FTR_SECTION
lwarx r7,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@ -713,6 +716,9 @@ restore:
mtctr r11
PPC405_ERR77(0,r1)
BEGIN_FTR_SECTION
lwarx r11,0,r1
END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
stwcx. r0,0,r1 /* to clear the reservation */
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))

22
include/asm-powerpc/cputable.h
View File

@ -138,6 +138,7 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
#define CPU_FTR_FPU_UNAVAILABLE ASM_CONST(0x0000000000800000)
#define CPU_FTR_UNIFIED_ID_CACHE ASM_CONST(0x0000000001000000)
#define CPU_FTR_SPE ASM_CONST(0x0000000002000000)
#define CPU_FTR_NEED_PAIRED_STWCX ASM_CONST(0x0000000004000000)
/*
* Add the 64-bit processor unique features in the top half of the word;
@ -261,25 +262,25 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
#define CPU_FTRS_7450_20 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7450_21 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_L3_DISABLE_NAP | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7450_23 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
#define CPU_FTRS_7455_1 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | CPU_FTR_L3CR | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
#define CPU_FTRS_7455_20 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_USE_TB | CPU_FTR_NEED_PAIRED_STWCX | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_L3_DISABLE_NAP | \
@ -289,31 +290,32 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447_10 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_NO_BTIC | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_NO_BTIC | CPU_FTR_PPC_LE | \
CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_L3CR | CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7447A (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE)
CPU_FTR_NEED_COHERENT | CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_7448 (CPU_FTR_COMMON | \
CPU_FTR_USE_TB | \
CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | \
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | \
CPU_FTR_NAP_DISABLE_L2_PR | CPU_FTR_HAS_HIGH_BATS | \
CPU_FTR_PPC_LE)
CPU_FTR_PPC_LE | CPU_FTR_NEED_PAIRED_STWCX)
#define CPU_FTRS_82XX (CPU_FTR_COMMON | \
CPU_FTR_MAYBE_CAN_DOZE | CPU_FTR_USE_TB)
#define CPU_FTRS_G2_LE (CPU_FTR_COMMON | CPU_FTR_MAYBE_CAN_DOZE | \